The present invention relates to a fluid mixing mechanism for introducing a controlled amount of gas into a liquid flowing through a conduit.
A siphon break is a well-known prior art construction which can function, within limits, to provide some mixing of a gas with a liquid until the siphon break interrupts all liquid flow at a certain level of suction on the liquid line or conduit. In a siphon break an air line (having a fixed, inner restriction) is connected into the interior of a fluid conduit. The conventional prior art siphon break serves the primary function of breaking or stopping the flow of liquid through the conduit under certain circumstances. Thus, in a case where the liquid flow through the conduit is produced by a siphoning action and it is desired to interrupt the siphoning flow when the suction decreases to a certain amount, the air tube can incorporate a fixed orifice which will permit air to bleed in to the interior of the liquid tube faster than the suction will draw the liquid through the tube, so that the suction or siphoning of the liquid is broken at that amount of suction (or at lower amounts of suction).
This prior art type of siphon break incorporates a fixed orifice that does not have any changing characteristics. The fixed orifice must be made large enough, or small enough, to do a particular job; but the fixed orifice might then be completely unsatisfactory for operation at any, or all, other conditions.
In many applications, there is a need to provide a controlled mixing of liquid and gas over a wide range of suctions (or other pumping of fluid flow) through the liquid conduit. The prior art, fixed orifice siphon break type constructions can not provide a controlled variation of the mixing of gas and liquid flow because the prior art fixed orifice type of siphon break construction cannot provide the required large variation in the ratios of gas to liquid flow with changing flow conditions.
It is a primary object of the present invention to control the mixing of a gas with a liquid flowing through a conduit in a way which avoids the problems of the prior art fixed orifice siphon break construction.
It is a related object of the present invention to introduce a controlled amount of gas into a liquid flowing through a conduit by a control mechanism which is constructed to produce a variable impedance to fluid flow through the control mechanism and to cause the impedance to vary in a non-linear relationship to the pressure differential across the flow control mechanism and to an acceleration of the flow through the control mechanism.